The Influence of Religion on Alcohol Use Initiation: Evidence for Genotype X Environment Interaction

Twin studies have generally been consistent in suggesting that there are important family environmental influences on whether or not one chooses to drink alcoho

Meta-analysis of Genome-Wide Association Studies for Extraversion: Findings from the Genetics of Personality Consortium

Extraversion is a relatively stable and heritable personality trait associated with numerous psychosocial, lifestyle and health outcomes. Despite its substantial heritability, no genetic variants have been detected in previous genome-wide association (GWA) studies, which may be due to relatively small sample sizes of those studies. Here, we report on a large meta-analysis of GWA studies for extraversion in 63,030 subjects in 29 cohorts. Extraversion item data from multiple personality inventories were harmonized across inventories and cohorts. No genome-wide significant associations were found at the single nucleotide polymorphism (SNP) level but there was one significant hit at the gene level for a long non-coding RNA site (LOC101928162). Genome-wide complex trait analysis in two large cohorts showed that the additive variance explained by common SNPs was not significantly different from zero, but polygenic risk scores, weighted using linkage information, significantly predicted extraversion scores in an independent cohort. These results show that extraversion is a highly polygenic personality trait, with an architecture possibly different from other complex human traits, including other personality traits. Future studies are required to further determine which genetic variants, by what modes of gene action, constitute the heritable nature of extraversion

The genetics of smoking initiation and quantity smoked in Dutch adolescent and young adult twins

Not much is known about the genetic and environmental determinants of various aspects of substance use in adolescents. This study examined whether the inheritance of initiation of tobacco use in adolescents is independent of the inheritance of the number of cigarettes smoked. Alternative multifactorial threshold models were applied to data on tobacco use in 1676 Dutch adolescent twin pairs. The three models that were considered are (i) the single liability dimension model, (ii) the independent liability dimension model, and (iii) the combined model (CM). The results showed that there is not one underlying continuum of liability to smoking. The CM was the best-fitting model. This model postulates that there are separate initiation and quantity dimensions but allows for the possibility that there are some individuals who are so low on the liability to level of consumption that they are not using tobacco. There were no differences between males and females in the magnitude of the genetic and environmental influences on individual differences in smoking initiation and quantity smoked. Smoking initiation was influenced by genetic factors (39%) and shared environmental influences (54%). Once smoking is initiated genetic factors determine to a large extent (86%) the quantity that is smoked